A storage area network (SAN) is a dedicated network that provides access to consolidated, block level data storage. SANs are primarily used to make storage devices accessible to servers so that the devices appear like locally attached devices to the operating system. A SAN typically has its own network of storage devices that are generally not accessible through the local area network by other devices.
A SAN switch is typically a fibre channel switch that allows for the creation of switched fabric, where network nodes connect with each other via one or more network switches.
Storage virtualization uses virtualization concepts as a tool to enable better functionality and more advanced features within and across storage systems. SAN virtualization solutions provide high availability and redundancy by using a clustered system consisting of multiple controllers. These controllers may provide a caching mechanism to speed up application input/output (I/O). In systems that employ cache mirroring, application writes are acknowledged after replicating the write data to alternate controller caches. By employing cache mirroring, a system may protect cached data from controller failures.